A number of techniques are known for clearing obstructions in coronary arteries. These include by-pass surgery, the use of a "balloon" to expand the arterial wall in the region of the obstruction, the use of a cutter passed along the artery to remove the obstruction and the use of a drill which is also passed along the artery to pulverise the obstruction. By-pass surgery is a major operation and is expensive. The use of surgical instruments in the above-described alternative methods involves the risk that the instrument which is passed along the artery will puncture the arterial wall during use or during passage along the artery to the location at which the obstruction is to be cleared. Additionally, the use of a drill which pulverises the obstruction involves the risk of the pulverised material lodging in another part of the body and causing damage there.
It is an object of the present invention to provide a surgical instrument for clearing obstructions in ducts in which the above described problems can be obviated or mitigated.